On 13/01/2023 03:15, Dixit, Ashutosh wrote:
On Thu, 12 Jan 2023 18:27:52 -0800, Vinay Belgaumkar wrote:Reading current root sysfs entries gives a min/max of all GTs. Updating this so we return default (GT0) values when root level sysfs entries are accessed, instead of min/max for the card. Tests that are not multi GT capable will read incorrect sysfs values without this change on multi-GT platforms like MTL. Fixes: a8a4f0467d70 ("drm/i915: Fix CFI violations in gt_sysfs")We seem to be proposing to change the previous sysfs ABI with this patch? But even then it doesn't seem correct to use gt0 values for device level sysfs. Actually I received the following comment about using max freq across gt's for device level freq's (gt_act_freq_mhz etc.) from one of our users: ----- On Sun, 06 Nov 2022 08:54:04 -0800, Lawson, Lowren H wrote: Why show maximum? Wouldn’t average be more accurate to the user experience? As a user, I expect the ‘card’ frequency to be relatively accurate to the entire card. If I see 1.6GHz, but the card is behaving as if it’s running a 1.0 & 1.6GHz on the different compute tiles, I’m going to see a massive decrease in compute workload performance while at ‘maximum’ frequency. ----- So I am not sure why max/min were previously chosen. Why not the average?
I think we still have time to just either stop exposing the global files on multi-tile platforms (all are under force probe), or return some error from them.
IMO it's not kernel's job to provide any representation here - be in min, max, sum or average (different "blending" methods were discussed for different files) - all of them have some potential to be misleading from different angles.
Regards, Tvrtko
